Many thanks to Erik Andresen, Nina Dahl and colleagues at the Norwegian Institute for Air Research (NILU) for the preparation and analysis of passive diffusion
Reliability of nitrogen dioxide passive diffusion
tubes for ambient measurement: in situ properties of the triethanolamine absorbent, Journal of Environmental Monitoring 2: 307-312.
In view of the observed pH--solubility profile, for a 50% v/v propylene glycol:water vehicle, a pH between 4 and 5 was suggested by the authors to provide the most favourable environment for passive diffusion
since the concentration of unionised methotrexate would be optimal.
of SA through cellulose acetate membrane was compared with iontophoretic diffusion by various current profiles.
We may only speculate that oral thyroxine is administered as sodium salt that is less lipophilic than the native hormone, which enters target cells both through passive diffusion
and in a carrier-mediated, inhibitable way.
Specifically, the objectives of this study were to evaluate: 1) the limiting nutrient of periphytic algae using a passive diffusion
periphytometer; 2) the content of easily exchangeable nutrients in sediments; and 3) sediment and water column dissolved P equilibrium in these streams.
Gas exchange is accomplished through the process of passive diffusion
of oxygen and carbon dioxide across the alveolar-capillary membrane.
The authors outline the mechanisms whereby secretion, active pumping, passive diffusion
or gradient diffusion at the cellular level cause nucleation on particulates, on cell surfaces, or genetically programmed precipitation in organic matrices either on or within cells.
Molecules traverse the membranes either by passive diffusion
or active transport.
For example, a passive diffusion
periphytometer is used to assess algal nutrient limitation and assimilation capacity in streams; this technology may be used to develop nutrient management thresholds for streams based on comprehensive measures of nutrient assimilative capacity.